Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, 2011 / A multifactor ecological integrity index, focusing on freshwater ecosystems on a quaternary
catchment scale, can be of great benefit to conservation planning. No ecological integrity
index has previously been developed for South African quaternary catchments. In this study
an index was developed based on three environmental surrogates: land cover, river integrity
and fish species conservation status, with the intention of identifying quaternary catchments
of highest conservation concern. By developing such an index, the aim was to provide a
general indication of the degree to which catchments have been transformed from a natural
environment to a human altered environment, thereby identifying catchments most in need
of conservation.
For the three available datasets, indices were developed using a five category point-scoring
system. A score of one indicates a completely degraded environment and a score of five
indicates a pristine environment. The original land cover data consisted of 49 different land
cover types which were reduced to five land cover transformation scores. Available river
integrity data already existed in five categories and a numerical score of one to five was
applied to each category. Fish species conservation status was scored according to the
IUCN red data list classifications on a similar basis.
Subsequently, a weighted mean score expressed as a percentage was calculated for the
three indices for each quaternary catchment. These indices indicate the degree of
change/transformation from a natural system (100%) to a largely degraded system (20%).
Ultimately, an ecological integrity index was calculated as a mean value of the three related
but independent indices. However, the results of the developed ecological integrity index
were not representative of real world conditions. This is largely attributed to the lack of
complete data found in two out of the three datasets used in the study. Some of the main
limitations encountered were the lack of river segment definitions within each catchment and
the incomplete and un-systematic collected fish species data records. The land cover data,
on the contrary, was of high definition and high standard. It is recommended that in the
interim, the developed land transformation index, based on a detailed analysis of land cover,
be used as an indicator index of ecological integrity of catchments
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/10417 |
| Date | 15 September 2011 |
| Creators | Van Dam, Carien Engela |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf |
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